eng
Quantum-mechanical study of magnetic properties of superalloy nanocomposite phase Fe2AlTi
nusl-391445
Slávik, Anton
Miháliková, Ivana
Friák, Martin
Všianská, Monika
Šob, Mojmír
NANOCON 2017. International Conference on Nanomaterials - Research & Application /9./
Brno (CZ)
20171018
LM2015069
GA17-22139S
GA16-24711S
GA MŠk
GA ČR
GA ČR
2018
Ab initio calculations
Fe-Al based superalloys
Fixed-spin-moment
Nanocomposites
http://hdl.handle.net/11104/0289458
http://www.nusl.cz/ntk/nusl-391445
The L21-structure Fe2AlTi intermetallic compound is one of the two phases identified in Fe-Al-Ti superalloy nanocomposites. Experimental data related to low-temperature magnetic properties of this Heusler compound indicate that magnetic moment is about 0.1 Bohr magneton per formula unit. In contrast, previous quantum-mechanical calculations predicted Fe2AlTi to have much higher magnetic moment, 0.9 Bohr magneton per formula unit. In order to solve this discrepancy between the theory and experiment we have performed a series of quantum-mechanical fix-spin-moment calculations and compared our results with those for non-magnetic state. It turns out that the total energy of the non-magnetic state is only by 10.73 meV/atom higher than that of the magnetic state. When applying Boltzmann statistics to this very small energy difference we predict that the non-magnetic state appears at non-zero temperatures with significant probabilities (for instance, 22.36 % at T = 100 K) and reduces the overall magnetic moment. As another mechanism lowering the magnetization we studied selected shape deformations, in particular trigonal shearing. Fe2AlTi exhibits a compression-tension asymmetry with respect to these strains and, for example, the strain 0.08 destabilizes the spin-polarized state, leaving the non-magnetic state as the only stable one.
6 s.
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